Homeschool.Com
Sell on-line courses, and kits and curriculum by subject. Also message boards and homeschooling FAQ.

Oak Meadow
Provides curriculum materials "that respect the spirit of children. We believe that children learn best through
doing. Our materials are designed to engage the whole child and foster a joy of learning while providing a solid academic education."
Offers onlline courses for grades 6-12, a bookstore, catalogs (available in PDF), FAQs,
curriculum overviews by grade, statement of beliefs, etc. Oak Meadow curriculum is based loosely on the Rudolf Steiner/Waldorf School
principles.

A Beka Books
Claims to be the largest Christian textbook publisher in the world. Also publishes videos. I found its online content weak.

Bible Study Guide For All Ages
Sells a Bible curriculum for Sunday schools, homeschoolers, Bible classes, small groups, and family devotionals. There are four units (one per year),
each with 104 lessons, visuals, application suggestions, background information, review system, memory-work and drills. The entire Bible can be covered in 4 years
studying 2 lessons per week. Some Old Testament and some New Testament books are studied each year. Web site offers some sample pages, including beginner activity pages (ages 3-7),
intermediate activity pages (ages 8-12). Also sells timelines and maps.

Resources are ranked within each topic; the first listed is the most useful and the last the least useful, in my opinion. This is based on depth and breadth of content, quality of links, ease of use, organisational structure, and general appearance.

A resource ranked last may be a great resource for a limited audience, or it may be an OK resource that's meant for a large audience. I have not listed resources I found to be anything but great or good, except for national organisations. Suggestions are always welcomed.